Patent GB-721434-A (GB)
Title: Device for determining minute variations in inclination of a tilting body and for optically neutralising such variations as in stabilising the line of sight of an optical instrument
IPC: G01C9/12
Filed: 1950-10-30
Abstract: 721,434. Cliriometers; optical systems. ZEISS-OPTON OPTISCHE WERKE OBERKOCHEN GES. Oct. 30, 1950 [Nov. 9, 1949], No. 26476/50. Classes 97 (1) and 97 (2). Minute variations in the inclination of a tiltable body from the horizontal are made apparent by a pendulum device comprising a quadrilateral framework constituted by the tiltable body and a pendulum body coupled thereto by two links with means connected to the two bodies for indicating the relative movement therebetween. The device is used in an optical instrument such as a telescope or reading microscope for optically neutralizing deviations of the instrument to stabilize the line of sight in which case optical means are mounted on the tiltable and pendulum bodies. The coupling said bodies may be formed by non- rigid members such as wires or ribbons and to avoid twisting of the linkage two pairs of links may be used arranged in pyramidal formation or more than two parallel pairs may be used. As shown in Fig. 4, the said bodies consist of rolls 11, 12 interconnected by pairs of ribbon links 13, 14 having centres of swing variable with tilt. The tiltable roll 11 is fitted with a perpendicular shaft 15 seated on the instrument &c. 16 in the plane of inclination. Roll 12 carries an index 17 moving over a scale 18 carried on roll 11. Since the rolls are of equal diameter the linkage arrangement does not affect the amplification of the tilt angle shown by the index 17, the amplification being obtained by virtue of the centre of gravity of the pendulum body 12 and index 17 being above the axis of the roll 12 as explained in the Specification. The links may be uncrossed and the two inner links merged into one link and the resulting three links arranged in pyramidal fashion. The links may have constant centres of swing as shown in Fig. 5 which represents an arrangement for stabilizing the line of sight of a telescope which may be initially set by means of a box bubble 26. The tiltable body 49 secured to the telescope casing is connected to the pendulum body 50 by two pairs of crossed links 51 in parallel planes and attached by means of straps 21, 22 terminating with the bodies. The reticule 23 is supported on the pendulum body 50 with its plane at right angles to the plane of inclination of the telescope and its weight is compensated by mass 25. In an alternative construction using a fixed reticule in the telescope an arrangement of bodies and links similar to that shown in Fig. 4 is used as well as one employing part rolls, each roll or part roll carrying a reflecting prism located to reflect the light from the objective to the reticle. A damping cylinder and plunger device is provided to damp the pendulum swings. The link ribbons may be uncrossed and such an arrangement in a reading microscope is described. The movements of the pendulum body may be used to influence the circuits of an amplifier used for stabilizing apparatus such as a sextant for determining elevation angles.